Solve for $a$ : $22 = 30 + a$
Subtract $30$ from both sides: $ \begin{eqnarray} \\ \hphantom{22 {- 30}} &\hphantom{=}& \hphantom{a} \\ 22 &=& 30 + a \\ \\ {-30} && {-30} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 22 {- 30} &=& a \\ \end{eqnarray} $ Simplify. $ a = -8$